The present invention relates to the detection of ink level in printers and plotters and like mechanisms and, more specifically, to the detection of an ink out or nearing an ink out condition in a printer or plotter.
Several printer and plotter arrangements are known in the art. Each of these arrangements provide some type of print head that is coupled to an ink supply. The ink supply may be formed integrally with the print head or be detachably coupled thereto. Manufacturers of prior art printers and plotters include Hewlett-Packard, Canon and Epson, amongst others. In the text that follows, the terms printer and plotter are referred to collectively with the term printer.
Some prior art printers have an ink level or ink out detection mechanism. Printer ink level detection mechanisms are known that utilize mechanical, electrical, optical and pressure based detecting techniques. While beneficial in providing some degree of ink level indication, these prior art detection mechanisms tend to be disadvantageous for one or more of the following reasons: (1) they are not accurate enough at low ink volume, causing a manufacturer to put more ink in a cartridge to accommodate for measurement errors; (2) they are undesirably expensive; (3) they are not capable of functioning properly with higher performance printers; and (4) the detecting sensors are coupled directly to or otherwise provided with the ink cartridges such that the sensors are discarded along with spent ink cartridges.
Accordingly, embodiments of the present invention comprise ink level detection mechanisms and methods that utilize the pressure effects of a collapsing ink bag to detect and quantify a near out of ink condition.
It is another object of the present invention to provide an ink level detection device that is relatively economical to manufacture and operate.
It is another object of the present invention to provide an ink level detection device that may be implemented separately from an ink supply for which it detects ink volume level.
It is also an object of the present invention to provide an ink level detection device that maximizes the amount of usable ink (i.e., decreases wasted ink) by increasing the accuracy with which on out of ink condition is determined.
These and related objects of the present invention are achieved by use of a pressure based ink out detector as described herein.
The attainment of the foregoing and related advantages and features of the invention should be more readily apparent to those skilled in the art, after review of the following more detailed description of the invention taken together with the drawings.